Early space structures were fully assembled on earth prior to launching into space, and their size was limited to the cargo volume of the launch vehicle. Subsequent structures comprised ingenious folded, compressed, or rolled high-density assemblies that would unfurl, deploy, or expand upon arriving in space to form structures displacing a volume many times larger than the original stowage volume provided by the launch vehicle.
More sophisticated and complex structures for earth orbit deployment have been developed. Some such structures are to be manufactured in space by roll forming and welding of densely packaged spooled strip stock, usually of aluminum, thermoplastic graphite epoxy, or other composite material. Pulltrusion or rolltrusion forming at elevated temperature is used on the composite materials, and cold roll forming is the usual forming method employed on aluminum.
For structures of increased size, which requires volumes of material beyond the capabilities of these methods to produce, a new technique is required that will utilize the technologies and advantages of these prior assembly and deployment methods and will additionally possess the capabilities to produce structures vastly larger in size. Such a technique must be highly mechanized and automated to have the performance and cost effectiveness required of it.